DE1096607B - Process for the production of linear, highly crystalline head-to-tail polymers from ª ‡ -olefinic hydrocarbons - Google Patents

Description

Process for the production of linear, highly crystalline head-to-tail polymer aten from α-olefinic hydrocarbons The invention relates to polymers of a-olefinic hydrocarbons of the general formula C H2 = CII R, in which R denotes an alkyl radical.

The subject of previous patent applications by the inventor are highly crystalline, practically linear head-to-tail high polymers of α-olefinic hydrocarbons of the formula C H2 = C HR and process for their preparation. With these Process the olefinic hydrocarbons in the presence or absence an inert solvent with a by reaction of solid compounds one Transition metal with organometallic compounds of lead, tin, aluminum, Magnesium or zinc catalyst obtained at temperatures from -80 to +2200 C. brought into contact at normal or a pressure of a few atmospheres.

The crude polymerization products obtained in this way generally exist from mixtures of individual polymers with different molecular weights.

These mixtures contain crystallizable products in amounts that depend on the type of catalyst used.

When using catalysts that are predominantly crystalline polymers deliver, such as B. Catalysts made of TiCls and aluminum alkyls fall in the above-mentioned process polymers with a very high average Degree of polymerization, d. H. with a very high average molecular weight at.

The actual average degree of polymerization may vary depending on the the polymerization conditions vary within a very wide range and can adjust within certain limits by changing the temperature, especially when the working temperatures are in the upper part of the above-mentioned range. To a certain extent, the average degree of polymerization can also through Changing the quantitative ratio of metal compound to organometallic compound from which the catalyst is made.

The extent to which the average degree of polymerization by -die Variation of these two factors without a simultaneous significant effect on the The degree of crystallization can be influenced, however, is strictly limited, i. H. the crystalline state is a function of the average degree of polymerization.

It has now been found that highly crystalline polymers with a on average a much lower degree of polymerization than previous polymers with the same crystallinity; can be produced in that the polymerization in Presence of molecular hydrogen, preferably at low Partial pressure is carried out.

The invention relates to a method for the production of highly crystalline, linear head-to-tail polymers of a-oleänisdn hydrocarbons of the general Formula CH2 = CHR, in which R is an alkyl radical, by polymerization with a Catalyst obtained by reacting solid compounds of a transition metal, whose valence is below its highest, with metal alkyl compounds, these polymers having a significantly lower molecular weight than head-to-tail polymers with the same degree of crystallization under the same conditions, however can be produced in the absence of molecular hydrogen.

The polymerization is preferably carried out in the presence of an inert hydrocarbon solvent carried out.

Polymers produced according to the invention can be processed during processing on objects better than known polymers with the same degree of crystallinity handle.

Apart from reducing the unsaturation through reaction with the double bonds during the polymerization there is the only one noteworthy Effect of the hydrogen used according to the invention on - the nature of the Product in a reduction in the degree of polymerisation of this product. if so two polymerizations are carried out under identical conditions, where in one case molecular hydrogen is present and in the other not, they have obtained products have the same crystallinity and differ only in their average degree of polymerization and the degree of their unsaturated state.

The effect of hydrogen on the average degree of polymerization can even be observed at very low hydrogen concentrations. In general the hydrogen should be at a partial pressure of 0.01 to 1-00 atm. be used, wherein the magnitude of the partial pressure depends on the desired average degree of polymerization depends and can be determined by experiment.

If necessary, partial pressures outside of the specified Area can be used.

The catalysts preferred in the process according to the invention are those made from low valence titanium halides and aluminum alkylene.

In a process according to the invention, the catalyst is in a introduced a suitable autoclave, then a certain amount of an aliphatic Hydrocarbon solvent, for example n-heptane, added and the autoclave evacuated; thereafter the desired amount of electrolytically generated hydrogen and finally the monomers to be polymerized are added and with heating began. This method can of course be varied, for example by using different, continuous or discontinuous types the addition of hydrogen. After that, the polymerization takes place at the required temperatures (preferably at about 1000 C) and pressures carried out. After the end of the polymerization the polymers are first treated in the autoclave with an alcohol such as butanol, to decompose the organometallic compounds, then washed with acetone and then dried.

The effect of hydrogen on the average degree of polymerization of the product can be obtained from a comparison of the intrinsic viscosity values in tetrahydronaphthalene can be seen at 1350 C from dry, crude polymers using different amounts of hydrogen were produced.

A number of results obtained in the manufacture of polypropylene are contained in the drawing, which depend on the intrinsic viscosity of the partial pressure of the hydrogen used.

The yields of polymers in the presence of hydrogen are generally not lower than when working without hydrogen when the the amount of hydrogen supplied to sufficient limits for this purpose (approx. 0.5 Moles per 100 moles of hydrogen + olefin). The procedure described therefore has practical value for setting the degree of polymerization of the polymers α-olefinic compounds.

In the presence of very large amounts of hydrogen becomes the degrading Effect on the degree of polymerization increased. The yield of polymers will, however considerably reduced.

Example 1 A series of experiments on the polymerization of propylene were carried out in a 2 l shaking autoclave, each after removal the air by evacuating first a catalyst made of 4g titanium trichloride and 6 g iithyl aluminum monochloride, then 500 cc n-heptane and then the desired Amount of hydrogen to be introduced into the autoclave. Eventually 800 cc becomes liquid Propylene was added and the whole thing was heated at 750 ° C. for 12 hours while shaking. That The polymer obtained from the autoclave is first treated with butanol at 600.degree. C. and then washed with acetone and dried.

The intrinsic viscosity of the dry polymer is in tetrahydronaphthalene determined at 1350 C; then the polymer is extracted with hot n-heptane; the residue that then remains consists in any case of a highly crystalline one Polymer.

The results of the tests carried out with different amounts of hydrogen are given in the table below. Boundary polymer added Attempt amount of hydrogen viscosity in residue No. Tetrahydronadl Heptane No moles of H2 I atmospheres naphthalene extraction per 100 moles at room- at 1350 C tnGewidits- Propylene temperature *) percent i - - 6.36 86.6 2 0.02 0.03 3.43 84.2 3 0.08 0.13 2.17 84.5 4 0.46 0.66 1.09 85.1 5 0.70 1 1.14 75.3 6 1.38 2 0.78 76 *) Free volume of the autoclave: 1.5 1.

Example 2 3.8 g of titanium trichloride and a solution of 6.5 g of triethylaluminum in 500 cc of n-heptane are introduced into a 1.7-1 autoclave under nitrogen. Then 300 g of a propylene-propane mixture consisting of 910/0 of propylene are added added and shortly thereafter hydrogen up to a pressure of 140 atm. introduced. The temperature is increased to 760 ° C. and the autoclave is moved for 15 hours. In this A significant reduction in pressure is observed over time.

The polymerization product is then removed.

After cleaning and drying, this product consists of 53 grams of one Polymers with an intrinsic viscosity of 0.22. The one after extraction with n-heptane remaining residue consists of highly crystalline polypropylene with an intrinsic viscosity of 0.42.

If under the same conditions described above, but in the absence is worked by hydrogen, there are 235 g of a polymer. The residue from the extraction with hot n-heptane consists of highly crystalline polypropylene with an intrinsic viscosity of 4.5.

Example 3 750 g of butene with a 1-butene content of 60010 are used in a 3-1 autoclave in the presence of a catalyst made from 22.8 g of triethylaluminum and 15 g Titanium trichloride polymerized, with 750 ccm of benzene as Solvents are added. After 12 hours of heating at 700 ° C. with stirring and after the cleaning indicated above, 404 g of a polymer with a Intrinsic viscosity of 1.49 in tetrahydronaphthalene at 1350 C obtained. During the extraction with hot ether becomes a highly crystalline residue with a yield of 70.4 po obtain.

With an exact repetition of the experiment, but after the Introducing the butene and, before heating, hydrogen to a pressure of 10 Atm. (3.3 mol per 100 mol of hydrogen + butene) is fed, 136 g of one Polymer obtained with an intrinsic viscosity of 0.93, of which 74.1 percent by weight are insoluble and highly crystalline in hot ether.

Example 4 875 g of butene with a 600% butene-1 content become upon introduction of hydrogen up to a pressure of 1.6 atm. (0.46 moles per 100 Mol of hydrogen + butene) under the same conditions 376 g of a dry polymer obtained with an intrinsic viscosity of 1.25. The highly crystalline residue of the ether extraction corresponds to 74.9 percent by weight.

In a comparative experiment, the procedure is as in Example 3, but 830 g of butene with a butene-1 content of 60% were used. After heating for 11 hours at 700 C a polymer is obtained, which after washing with butanol and after Drying weighs 411 g and has an intrinsic viscosity of 1.57. The highly crystalline The residue after the ether extraction corresponds to 70.5 percent by weight of the crude polymer.

PATENT CLAIM: 1. Process for the production of linear, highly crystalline Head-to-tail polymers of α-olefinic hydrocarbons of the general Formula CH2 = CHOR, in which R is an alkyl radical, with a predetermined molecular weight by means of polymerization catalysts from compounds of transition metals and Metal alkyl compounds together with molecular hydrogen, thereby marked, that a mixture of said olefinic monomers and molecular hydrogen with catalysts made from solid compounds of a transition metal, its valence is below its highest, and metal alkyl compounds are polymerized.

Claims (1)

2. The method according to claim 1, characterized in that the molecular Hydrogen with partial pressures from 0.01 to 100 atm. is applied. 3. Process according to Claims 1 and 2, characterized in that propylene or butene-1 are used as monomeric substances. 4. Process according to Claims 1 to 3, characterized in that polymerization in the presence of an inert hydrocarbon as solvent is carried out. 5. Process according to Claims 1 to 4, characterized in that a low-valent titanium halide and aluminum alkyl catalyst is used will. Publications considered: Documentation laid out by the Belgian Patent No. 543,941.